Sendgrid webhook signature verification failures in node js

I am trying to verify the signature of Sendgrid's webhooks in node.js but I am getting consistent verification failures.
I have tried using the "Test Integration" feature, "Test emails", but also actual sends but all these options end up with verification failures.

I am using the official helper for node.js, available here: https://github.com/sendgrid/sendgrid-nodejs/blob/main/packages/eventwebhook/src/eventwebhook.js

Please note that this code is implemented on a Cloud Function.

import * as functions from "firebase-functions";
import { EventWebhook } from "@sendgrid/eventwebhook";

export const handleSendGridWebhookEvents = functions
  .region(...fb.REGIONS)
  .https.onRequest(async (req, resp) => {

    const signature =
      (req.get("x-twilio-email-event-webhook-signature") as string) ??
      "";
    const timestamp =
      (req.get("x-twilio-email-event-webhook-timestamp") as string) ??
      "";

    if (!signature || !timestamp) {
      resp.json({
        error: "Webhook handler failed",
      });
      throw new Error("Sendgrid headers missing");
    }

    const verify = new EventWebhook();
    const payload = req.body;
    const publicKey = process.env.SENDGRID_WEBHOOK_PK

    try {
      const ecdsaPublicKey = verify.convertPublicKeyToECDSA(publicKey);
      const isVerified = verify.verifySignature(
        ecdsaPublicKey,
        payload,
        signature,
        timestamp
      );
      console.log({ isVerified }); // Always returns false
      resp.status(200);
    } catch (e) {
      throw e;
    }
    resp.json({ received: true });
  });

I have tried using the public key directly as well without the initial conversion to ECDSA but no luck there either.

Are there any additional steps required to verify the signature? Or anything wrong with the code above...?

Thanks

I finally had a Eureka moment.

The payload that needs to be passed in the function needs to be the rawBody of the request, not the body.

I have updated my code to reflect this.

Which makes it the only working example I have seen in Node.js.

import * as functions from "firebase-functions";
import { EventWebhook } from "@sendgrid/eventwebhook";

export const handleSendGridWebhookEvents = functions
  .region(...fb.REGIONS)
  .https.onRequest(async (req, resp) => {

    const signature =
      (req.get("x-twilio-email-event-webhook-signature") as string) ??
      "";
    const timestamp =
      (req.get("x-twilio-email-event-webhook-timestamp") as string) ??
      "";

    if (!signature || !timestamp) {
      resp.json({
        error: "Webhook handler failed",
      });
      throw new Error("Sendgrid headers missing");
    }

    const verify = new EventWebhook();
    const payload = req.rawBody;
    const publicKey = process.env.SENDGRID_WEBHOOK_PK

    try {
      const ecdsaPublicKey = verify.convertPublicKeyToECDSA(publicKey);
      const isVerified = verify.verifySignature(
        ecdsaPublicKey,
        payload,
        signature,
        timestamp
      );
      console.log({ isVerified }); // Yes!
      resp.send({ received: true }).status(200);
    } catch (e) {
      throw e;
      resp
        .send({
          error: "Webhook handler failed.",
        })
        .status(500);
    }
  });